Boa noite pessoal,

Estou tentando instalar o pacote AER, mas não consigo me dá a mensagem de erro:

Attaching package: 'zoo'

The following object(s) are masked from 'package:base':

    as.Date

** help
*** installing help indices
** building package indices ...
** testing if installed package can be loaded
Error : object 'nobs' not found whilst loading namespace 'AER'
ERROR: loading failed
* removing ‘/home/asantos/R/i686-pc-linux-gnu-library/2.12/AER’
Warning in install.packages :
  installation of package 'AER' had non-zero exit status

The downloaded packages are in
	‘/tmp/Rtmpo2u5y0/downloaded_packages’

Não sei se pode ser isso mais tenho instalado dois pacotes com o nome zoo,

Obrigado,

Alexandre